I knew that Orbital ATK would think about launching more Cygnus spacecrafts atop Atlas V; it was a matter of time.

After OA-7, Antares would have launched seven times plus the Orb-3 failure in 2014. Compared to 73 successes out of the previous 74 Atlas V flights, I think one of the reasons that the latter would be used for Cygnus is because of its higher success rate.

Don't discount the effects of flight frequency.

It's a huge cost to have a LV supply chain, support and dev costs spread over few launches. At a time where even with ULA's incredible history with Atlas V, they are fighting the costs battle tooth and nail.

It's just too expensive to keep alive your own LV, it may seem.

add:(I'd suspected when they flew first on Atlas that this would happen. Also have been quite skeptical of RD-181 not due to costs but due to other issues with RD-191/193, and Angara's delays/issues.) And having been skeptical before that of AJ-26's unique history of storage/test.

Is it more cost-effective for OA to supplement Cygnus/Antares launches with Cygnus/Atlas V launches?

Is an outside vendor's "ride" less expensive than purchasing their own rocket?

I don't think Orbital ever really embraced Antares... They had to pretty much be dragged into COTS and CRS as NASA was desperate for another COTS entry besides SpaceX. NASA were so desperate that they even bent over backwards and built the integration and processing hangar at Wallops for Orbital. Orbital (and then OrbitalATK) went ahead with it because there was some slight profit to be had... But with the mishap and more competition, I think the end of Antares may be near. Especially if OrbitalATK doesn't even want to use it for their *own* missions to ISS.

How many Antares have Orbital committed to integrate at this point? I'm presuming they'll fly all the first and second stages they bought, but how many is that? The tea leaves sure sound like the number won't be more than what they've already contracted.

So you draw the conclusion that Antares launcher offering will end in the not to distant future.It's NASA that prefers launching Cygnus on Atlas V above Antares, because of the higher payload capability.OATK stil has to launch OA-8 to OA-11 right for COTS1 extended?. OA-8 will launch on Antares and I expect at least one more. Some of them will launch on Atlas V.

Secondly, both Atlas V and Antares use RD-18x engines, not so much difference there. I agree with the launch cost spiraling out of control. Does someone know how many tanks OATK has laying around? I think that OATK will launch those; Or Yuzhnoye buys them back for Cyclone-M.

But I think OrbitalATK primarily likes keeping Antares around as a bargaining chip. And having low cadence launch vehicles seems to be Orbital's weird specialty...

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Orbital ATK ordered eight RD-181 engines in 2015. That's enough for four Antares launches, including one that has already flown. The company has an option to buy as many as 30 engines.

- Ed Kyle

The SFN article below said that OA-8 through OA-12 are baselined for Antares.

Quote

“The first mission type is a pressurized cargo mission on Antares, very similar to what we’re flying on OA-8 to OA-11,” DeMauro said in a July 11 interview. “Those will have a little bit more cargo capacity, but it’s an Antares-based mission.”

NASA has authorized the first of the six Cygnus flights planned from 2019 through 2014. Named OA-12, that mission will launch on an Antares booster from Wallops Island with pressurized cargo.

“We have six missions that have been contracted for on CRS-2,” said Frank Culbertson, a former astronaut and president of Orbital ATK’s space systems group. “The first one has been given a go-ahead for activity, so we are doing long-lead purchasing, beginning the process to … start building the structure. That one should launch in, we hope, 2019.”

Note this was a pre-merger article, more than a month ahead of the merger. And that the launch of OA-8 also was delayed to the following month.

When I read it more critically, it reads more like a business continuity piece meant to insure that the CRS contracts would continue to be serviced. No talk of expansion of capabilities, new vehicles, or the like.

You also couldn't tell if the advanced purchases were both vehicles or just in reference to Cygnus.

Acquirers often cancel supply contracts for follow on business, because given the greater heft of the combined firm they can usually get a better deal.

So I'm still not convinced that the Antares manifest will stick that long. Perhaps fly out of the existing inventory, but without other payloads beyond Cygnus, and no follow on announcements for "Antares 300" ... seems like a "one trick pony" to me. Too easy to pull the plug after the following four and get a bulk deal for Atlas V.

Frank DeMauro said that OA's plan is to continue flying Cygnus on Antares, and that they currently have orders out to OA-13.

Quote

DeMauro said there are no plans to return to the Atlas 5 for the foreseeable future, as the company completes its original Commercial Resupply Services (CRS) contract and starts a follow-on award called CRS-2. “Our baseline plan is to continue to fly Cygnus on Antares,” he said. “We are ready to respond to our customer’s needs, if they should require something different, but for all of the rest of CRS-1 and so far for the CRS-2 missions we’re planning to do them on Antares.”

After this launch, Orbital ATK has three missions remaining on its CRS contract, OA-9, 10 and 11. No firm launch dates have been set, but DeMauro said OA-9 could launch as soon as the first quarter of 2018. OA-10 would then likely follow in the fall of 2018 and OA-11 in early 2019. DeMauro said later that NASA has ordered two Cygnus missions so far under its CRS-2 contract, OA-12 and 13.

It was reported that OA-5 and OA-8 both had slight overperformance putting their payloads into higher orbits than planned so models will be adjusted, which will also allow for slightly greater payload mass.

Frank DeMauro said that OA's plan is to continue flying Cygnus on Antares, and that they currently have orders out to OA-13.

Quote

DeMauro said there are no plans to return to the Atlas 5 for the foreseeable future, as the company completes its original Commercial Resupply Services (CRS) contract and starts a follow-on award called CRS-2. “Our baseline plan is to continue to fly Cygnus on Antares,” he said. “We are ready to respond to our customer’s needs, if they should require something different, but for all of the rest of CRS-1 and so far for the CRS-2 missions we’re planning to do them on Antares.”

After this launch, Orbital ATK has three missions remaining on its CRS contract, OA-9, 10 and 11. No firm launch dates have been set, but DeMauro said OA-9 could launch as soon as the first quarter of 2018. OA-10 would then likely follow in the fall of 2018 and OA-11 in early 2019. DeMauro said later that NASA has ordered two Cygnus missions so far under its CRS-2 contract, OA-12 and 13.

I take that as with over preformance.. they can do the Atlas profile with current Antares.. if they do decieced to get the up thrust with extended tanks.. they could do more such as the Super Cygnus if Nasa wanted it or might have to do that under Atlas..

They snuck another third stage option in at some point. Northrop Grumman's factsheet shows the options of the Star 48, Orbit Adjust Module (used to be called bi-propellant third stage), and now also shows an Orion 38 motor.

They snuck another third stage option in at some point. Northrop Grumman's factsheet shows the options of the Star 48, Orbit Adjust Module (used to be called bi-propellant third stage), and now also shows an Orion 38 motor.

This new fact sheet also shows incremental improvement in performance, especially to LEO. 200 km x 38 deg payload is now about 7.8 tonnes, compared to 6.6 tonnes. LEO x 51.6 deg is 7.4+ tonnes compared to the previous 6.3 tonnes. 500 km sun synchronous orbit payload is now 3 tonnes for the 231 variant (OAM third stage). Antares 232 (STAR 48BV third stage) is listed at 1.6 tonnes to escape velocity (better than Delta 2H, better than the old Atlas Centaurs of the 1970s and 1980s, and better than China's CZ-3A). The old number was about 1.45 tonnes. Etc.

The new Orion 38 motor is not listed for escape missions. Perhaps it is aimed at elliptical earth orbit science missions?

These improvements are likely the upgrades mentioned recently for CRS-2, derived from increasing intertank and forward skirt structural margins, improving the Castor 30XL mass ratios, and so on. This was identified as the "Antares 230+" series by Orbital ATK last month.

Northrop Grumman has a potent bantam-weight rocket on its hands here, if it can keep costs in line.

Speaking of which, can anyone help decipher the Antares 23x+ characteristic energy versus payload chart? Where would GTO be, for example?

- Ed Kyle

I've never done this for a bound orbit, but using the definition that c3 = 2x specific orbital energy, we get

c3 = 2 * (v^2/2- u/r)

For GTO, v = 1596 m/s at the top of the orbit (if a 250 km perigee), r = 42157 km, and u for Earth is 3.986e14, then plugging in we get -16.4 km^2/sec^2.

EDIT: spelling

OK. So maybe roughly 2.1 tonnes to GTO for Antares 233 and 2.5 tonnes for Antares 232? Not too shabby for a Kerosene/LOX-Solid-Solid. Better than Delta 2 and GSLV Mk 2. About the same or slightly better than Ariane 40 and Atlas G/Centaur and Soyuz 2-1b/Fregat from Baikonur.